Process for the preparation of pivaloylacetic acid esters

Abstract

An improved process for the preparation of pivaloylacetic acid esters by decarbonylation of pivaloylpyruvic acid esters at elevated temperatures is described. The process is carried out in the presence of 0.01 to 5 percent by weight of a metal of sub-groups one to eight of the periodic system, which metal is in metallic and/or oxidic form. Initially, 30 percent of the pivaloylpyruvic acid ester to be converted is heated in the presence of the metal, and after conversion of the same there is added additional pivaloylpyruvic acid ester according to the rate at which the pivaloylpyruvic acid ester is converted.

What is claimed is: 
     
       1. In a process for the preparation of a pivaloylacetic acid ester by decarbonylation of a pivaloylpyruvic acid ester at an elevated temperature, the improvement which comprises subjecting pivaloylpyruvic acid ester to decarbonylation by heating the same in the presence of 0.01 to 5 percent by weight, relative to the total amount of the pivaloylpyruvic acid ester to be converted, of a metal in metallic and/or oxidic form, said metal being selected from the group consisting of copper, manganese, chromium and molybdenum, such that at most 30 percent of the total amount of the pivaloylpyruvic acid ester to be converted is heated and thereafter following the commencement of the reaction, adding the remaining amount of the pivaloylpyruvic acid ester to be converted according to the rate at which it is converted. 
     
     
       2. A process according to claim 1, wherein the metal is in an amount of 0.2 to 1% by weight. 
     
     
       3. A process according to claim 1 wherein said metal is copper. 
     
     
       4. A process according to claim 1 wherein said metal is manganese. 
     
     
       5. A process according to claim 1 wherein said metal is chromium. 
     
     
       6. A process according to claim 1 wherein said metal is molybdenum.